The present invention relates generally to hand-held optical scanners and, more particularly, to battery-powered, hand-held optical scanners in which the battery is charged by a generator assembly.
Optical scanners are used to produce machine-readable data which is representative of a scanned object, e.g. a page of printed text. Optical scanners employ line-focus systems to image scanned objects.
In a line-focus system, a light beam from an illuminated line object is imaged by a lens on a linear photosensor array which is positioned remotely from the line object. In an optical scanning device, the illuminated line object of the line-focus system is commonly referred to as a "scan line". The linear photosensor array is a single dimension array of photoelements which correspond to small area locations along the line object. These small area locations on the line object are commonly referred to as "picture elements" or "pixels". In response to light from its corresponding pixel location on the line object, each photoelement produces a data signal which is representative of the intensity of light which is impinged upon it. All of the photoelement data signals are received and processed by an appropriate data processing system which may subsequently store the data on a suitable medium or generate a display signal therefrom for reproducing an image of the object with a display device such as a CRT or printer.
Optical scanners and various components thereof are disclosed in U.S. Pat. No. 4,926,041 for OPTICAL SCANNER of David Wayne Boyd; U.S. Pat. No. 4,709,144 for COLOR IMAGER UTILIZING NOVEL TRICHROMATIC BEAM SPLITTER AND PHOTOSENSOR of Kent J. Vincent; and U.S. Pat. No. 4,870,268 for COLOR COMBINER AND SEPARATOR AND IMPLEMENTATIONS of Kent J. Vincent and Hans D. Neuman, which are each hereby specifically incorporated by reference for all that is disclosed therein.
A hand-held optical scanner is an optical scanner which is moved across a scanned object, e.g. a page of text, by hand. Most hand-held scanners have to date been powered by an external power source such as a power unit connected to a wall cutlet and in turn connected to the hand scanner by an electrical cable. Such external power sources have been deemed necessary due to the significant electrical energy required to operate the various scanner components. For example, the optical imaging assembly of a scanner typically comprises an illumination source such as a fluorescent bulk. The scanner photoelectric conversion assembly (typically a CCD) requires electrical energy as do the scanner speed detection circuitry and the scanner central processing unit. In the hand-held scanner of one preferred embodiment of the present invention, an onboard hard disk storage device is employed which also requires electrical energy to operate. It would be generally desirable to provide a hand-held scanner with an onboard power source and mass data storage assembly to eliminate the need for an external power connection or other connecting cables which "tether" the scanner to a fixed location. Such an arrangement would significantly improve the mobility and potential use applications for a hand scanner. However, one significant obstacle which must be overcome is the relatively short period of operation resulting from the use of an onboard power supply.
U.S. Pat. No. 4,703,186 of Nakayama et al., which is hereby specifically incorporated by reference for all that it discloses, describes a hand-held optical scanner with a speed control device. Several different speed control embodiments are described. In one embodiment, a friction disk is mechanically linked to a guide roller which rotates as the scanner is moved across a document. The friction disk is constructed to expand and move into frictional contact with a housing and thus produce a load resisting scanning motion when scanning speed exceeds a predetermined speed. In another embodiment, a flywheel and a rotating weight which moves radially outwardly relative to its rotation axis with increased scanning speed is employed to limit scanning speed and maintain a relatively smooth scanning speed. In another embodiment, the scanning unit is moved along a guide rail. An associated guide roller rotates, and thereby a DC motor is rotated in the reverse direction. "Then, the DC motor functions as a generator which produces a load practically proportional to the revolving rate thereof. The load thus produced tends to maintain the revolving rate of the guide roller at a fixed value, which controls the moving speed of the scanning unit for an approximate uniform motion."
Nakayama et al. thus describes certain methods for limiting scanning speed including use of a generator, but does not consider using electrical energy which is generated to charge a scanner battery.